Approximately half of the 230 residues of the gamma subunit of 7S NGF have now been sequenced and fragments covering most of the unstructured portions are in hand. Manual and automated methodology will be applied to complete these regions and the remaining segments, unaccounted for, will be generated by limited enzymatic cleavages. Attempts to crystallize one or more of the homogeneous forms isolated will be made and, if successful, single crystal x-ray diffraction analysis initiated. The purification of the soluble receptor will be continued using affinity chromatography. Determintion of the effect of various enzymatic modifications, e.g., phospholipase, will be initiated as well as studies on the quaternary structure of the receptor. Studies on the mechanism of the uptake of the receptor-hormone complex, with particular reference to the role of microtubules will be performed. Continued characterization of somatomedin from rat and its relationship to the human somatomedins should form the basis for detailed mechanistic studies of this insulin-related hormone. Similar studies are planned for relaxin.